Can i convert my procedural mesh terrain into landscape ?

hey there ! I search for a while but can’t find anything that fit my needs. I have a terrain created with a procedural mesh and it’s good. it has perlin noise and i can change the size all i want.

But now i need to add a lake and the water system didn’t work with procedural mesh so i’m in need for something to convert into a landscape OR some help to curve the terrain at some places to put a lake.

I’m new to unreal engine and i probably missing something, can someone give me a hand ? Thanks !